Led lamp with a lower end located under base of heat sink

ABSTRACT

An LED lamp includes: a lamp shell including a lamp head, a lamp neck and a sleeve, the lamp head connects to the lamp neck which connects to the sleeve; a passive heat dissipating element having a heat sink connected to the lamp shell, wherein the heat sink comprises fins and a base; a power source; a light emitting surface; a first heat dissipating channel formed in a first chamber of the lamp shell; a second heat dissipating channel formed in the heat sink and between the fins and the base; a lamp cover connected with the heat sink and having a light output surface and an end surface; wherein the base of the heat sink has a lower end located under the base, the lower end protrudes from the light emitting surface in an axis of the LED lamp; another side of the base of the heat sink, which is opposite to the lower end, has a back side, an end of each of the fins of the heat sink extends to connect with the back side, when the LED lamp is being hung, in an inward radial direction, the back side is upwardly slanted; wherein the fins of the heat sink include first fins and second fins, each of the first fins is divided into two portions in a radial direction of the LED lamp, the two portions are divided with a gap portion, each of the second fins has a third portion and a fourth portion extending therefrom, the fourth portions are located radially outside the third portions, the third portion is connected to the fourth portion through a transition portion, the transition portion has a buffer section and a guide section, a direction of any tangent of the guide section is separate from the gap portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser. No. 16/267,747 filed on 2019 Feb. 5, which claims priority to the following Chinese Patent Applications No. CN 201810130085.3 filed on 2018 Feb. 8, CN 201810479044.5 filed on 2018 May 18, CN 201810523952.X filed on 2018 May 28, CN 201810573322.3 filed on 2018 Jun. 6, CN 201810634571.9 filed on 2018 Jun. 20, CN 201810763800.7 field on 2018/07/12, CN 201810763089.5 filed on 2018 Jul. 12, CN 201810972904.9 filed on 2018 Aug. 24, CN 201811172470.0 filed on 2018 Oct. 9, CN 201811295618.X filed on 2018 Nov. 1, CN 201811299410.5 filed on 2018 Nov. 2, CN 201811347198.5 filed on 2018 Nov. 13, CN 201811378174.6 filed on 2018 Nov. 19, and CN 201811466198.7 filed on 2018 Dec. 3, the disclosures of which are incorporated herein in their entirety by reference.

FIELD OF THE INVENTION

The invention relates to lighting, particularly to LED lamps with a lower end located under base of heat sink.

BACKGROUND OF THE INVENTION

Because LED lamps possess advantages of energy saving, high efficiency, environmental protection and long life, they have been widely adopted in the lighting field. For LED lamps used as an energy-saving green light source, a problem of heat dissipation of high-power LED lamps becomes more and more important. Overheating will result in attenuation of lighting efficiency. If waste heat from working high-power LED lamps cannot be effectively dissipated, then the life of LED lamps will be directly negatively affected. As a result, in recent years, solution of the problem of heat dissipation of high-power LED lamps is an important issue for the industry.

OBJECT AND SUMMARY OF THE INVENTION

The LED lamp described in the present disclosure includes an LED (light emitting diode) lamp including a lamp shell including a lamp head, a lamp neck and a sleeve, the lamp head connects to the lamp neck which connects to the sleeve; a passive heat dissipating element having a heat sink connected to the lamp shell, wherein the heat sink comprises fins and a base, the sleeve of the lamp shell is located in the heat sink, the lamp neck projects from the heat sink, height of the lamp neck is at least 80% of height of the heat sink; a power source having a first portion and a second portion, wherein the first portion of the power source is disposed in both the lamp neck and the lamp head of the lamp shell, and the second portion of the power source is disposed in the heat sink of the passive heat dissipating element; a light emitting surface connected to the heat sink of the passive heat dissipating element and comprising LED chips electrically connected to the power source, wherein the light emitting surface and the heat sink are connected to form a heat transferring path from the LED chips to the passive heat dissipating element; a first heat dissipating channel formed in a first chamber of the lamp shell for dissipating heat generated from the power source while the LED lamp is working, and the first chamber is located between bottom of the LED lamp and an upper portion of the lamp neck; a second heat dissipating channel formed in the heat sink and between the fins and the base of the heat sink for dissipating the heat generated from the LED chips and transferred to the heat sink; a lamp cover connected with the heat sink and having a light output surface and an end surface, wherein the end surface is formed with a vent to allow air flowing from outside of the LED lamp into both the first heat dissipating channel and the second heat dissipating channel through the vent; wherein the first heat dissipating channel comprises a first end on the light emitting surface to allow air flowing from outside of the LED lamp into the first chamber, and a second end on the upper portion of the lamp neck of the lamp shell to allow air flowing from inside of the first chamber out to the LED lamp; wherein the second heat dissipating channel comprises a third end on the light emitting surface to allow air flowing from outside of the LED lamp into the second heat dissipating channel, and flowing out from spaces between every adjacent two of the fins; wherein the base of the heat sink has a lower end located under the base, the lower end protrudes from the light emitting surface in an axis of the LED lamp; another side of the base of the heat sink, which is opposite to the lower end, has a back side, an end of each of the fins of the heat sink extends to connect with the back side, when the LED lamp is being hung, in an inward radial direction, the back side is upwardly slanted; wherein the fins of the heat sink include first fins and second fins, each of the first fins is divided into two portions in a radial direction of the LED lamp, the two portions are divided with a gap portion, each of the second fins has a third portion and a fourth portion extending therefrom, the fourth portions are located radially outside the third portions, the third portion is connected to the fourth portion through a transition portion, the transition portion has a buffer section and a guide section, a direction of any tangent of the guide section is separate from the gap portion.

Preferably, a receiving space is encompassed by the lower ends for receiving the lamp cover, height of the lamp cover received in the receiving space does not project from the lower end.

Preferably, the light emitting surface includes three LED chip sets, each of the three LED sets has LED chips, the light emitting surface is divided into three areas comprising an inner ring, a middle ring and an outer ring, the three LED chip sets are respectively located in the inner ring, the middle ring and the outer ring, when at least one fin of the heat sink is projected onto a plane on which the LED chip set is located along an axial direction of the LED lamp, a projection of the at least one fin at least touches at least one LED chip of the LED chip set in the inner ring, the middle ring or the outer ring.

Preferably, any of the fins is projected onto a plane on which the LED chip set is located along the axial direction of the LED lamp, a projection of any of the fins at least touches at least one LED chip of the LED chip set.

Preferably, the LED chip set in the outer ring corresponding to the fins are greater than the LED chip set in the inner ring in number, the LED chip set in the outer ring has more LED chips than the LED chip set in the inner ring in number.

Preferably, a third aperture is located in a central region of the light emitting surface, and the third aperture forms an air intake of both the first heat dissipating channel and the second heat dissipating channel.

Preferably, the light emitting surface has an inner border and an outer border, both the inner border and the outer border separately upward extend along the axial direction of the LED lamp to form a region, an area of part of the fins inside the region is greater than an area of part of the fins outside the region.

Preferably, the sleeve corresponds to the third aperture.

Preferably, each LED chip of one of the LED chip sets on the light emitting surface is radially interlacedly arranged with any one LED chip of adjacent one of the LED chip sets on the light emitting surface.

Preferably, the projecting area of the gap portion directly exactly corresponds to an area that the LED chips are positioned on the light emitting surface.

Preferably, the first air inlet is projected onto the end surface in an axis of the LED lamp to occupy an area on the end surface, which is defined as a first portion, another area on the end surface is defined as a second portion, and the vent in the first portion is greater than the vent in the second portion in area.

Preferably, an inner reflecting surface is disposed inside the light output surface of the lamp cover, an outer reflecting surface is disposed in the outer circle of the array of LED chips.

Preferably, a second chamber is formed between the light output surface, the inner reflecting surface, the outer reflecting surface and the light emitting surface, the LED chips of the light emitting surface are located in the second chamber.

Preferably, the second chamber has first apertures and second apertures, the first apertures are configured to communicate with the outside, and the second apertures are configured to communicate simultaneously with both the first heat dissipating channel and the second heat dissipating channel.

Preferably, the light output surface is provided with holes to form the first apertures, the first apertures are annularly located at a circumferential portion of the light output surface.

Preferably, the inner reflecting surface is provided with notches to form the second apertures, the second apertures are annularly located at a circumferential portion of the inner reflecting surface.

Preferably, the ratio of the number of the second apertures to that of the first apertures is about 1:1˜2.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed descriptions, given by way of example, and not intended to limit the present invention solely thereto, will be best be understood in conjunction with the accompanying figures:

FIG. 1 is a structural schematic view of one embodiment of an LED lamp according to aspects of the invention;

FIG. 2 is a schematic cross-sectional view of the LED lamp of FIG. 1;

FIG. 3 is an exploded view of the LED lamp of FIG. 1;

FIG. 4 is a schematic cross-sectional view of the LED lamp of FIG. 1, which shows the first heat dissipating channel and the second heat dissipating channel;

FIG. 5 is a perspective view of the LED lamp of FIG. 1;

FIG. 6 is a structural schematic view of FIG. 5 without the light output surface;

FIG. 7 is a perspective view of another embodiment of an LED lamp according to aspects of the invention;

FIG. 8 is a schematic view of FIG. 7 without the light output surface;

FIG. 9 is a schematic view of an end surface of the lamp cover of an embodiment;

FIG. 10 is a schematic view of an end surface of the lamp cover, according to another embodiment of the present invention;

FIG. 11 is another view of the end surface of FIG. 10;

FIGS. 12A˜12G are schematic views of some embodiments of the lamp cover;

FIG. 13 is a perspective view of an LED lamp, according to another embodiment of the present invention;

FIG. 14 is a cross-sectional view of the LED lamp of FIG. 13;

FIG. 15 is a top view of the heat sink of the LED lamp of FIG. 13;

FIG. 16 is an enlarged view of portion E in FIG. 15;

FIG. 17 is a schematic view showing a vortex formed by air near the second fins according to another embodiment of the present invention;

FIG. 18 is a bottom view of the LED lamp of FIG. 1 without the lamp cover;

FIG. 19 is an enlarged view of portion A in FIG. 18;

FIG. 20 is a schematic view of the combination of the fins and the LED chips of an embodiment;

FIG. 21 is a schematic view of the combination of the fins and the LED chips, according to some embodiments of the present invention;

FIG. 22 is a schematic view of an embodiment of the light board;

FIG. 23 is a schematic view of another embodiment of the light board;

FIGS. 24A˜24C are perspective views of the power source, according to some embodiments of the present invention;

FIG. 24D is a main view of the power source of the embodiment of FIGS. 24A˜24C;

FIG. 25 is a cross-sectional view of the LED lamp of another embodiment;

FIG. 26 is a schematic view of an arrangement of the convection channels of the LED lamp of FIG. 25.

DETAILED DESCRIPTION OF THE EMBODIMENTS

To make the present invention understandable and readable, the following disclosure will now be described in the following embodiments with reference to the drawings. The following descriptions of various embodiments of this invention are presented herein for purpose of illustration and giving examples only.

FIG. 1 is a structural schematic view of an embodiment of an LED lamp according to certain aspects of the invention. FIG. 2 is a schematic cross-sectional view of the LED lamp of FIG. 1. FIG. 3 is an exploded view of the LED lamp of FIG. 1. As shown in the figures, the LED lamp includes a heat sink 1, a lamp shell 2, a light board 3, a lamp cover 4 and a power source 5. In this embodiment, the light board 3 is connected to the heat sink 1 by attachment for rapidly transferring heat from the light board 3 to the heat sink 1 when the LED lamp is working. In some embodiments, the light board 3 is riveted to the heat sink 1. In some embodiments, the light board 3 is screwed to the heat sink 1. In some embodiments, the light board 3 is welded to the heat sink 1. In some embodiments, the light board 3 is adhered to the heat sink 1. In this embodiment, the lamp shell 2 is connected to the heat sink 1, the lamp cover 4 covers the light board 3 to make light emitted from the light board 3 pass through the lamp cover to project out. The power source 5 is located in a chamber of the lamp shell 2 and the power source 5 is EC to the LED chips 311 for providing electricity.

FIG. 4 is a schematic cross-sectional view of the LED lamp. As shown in FIGS. 2 and 4, the chamber of the lamp shell 2 of this embodiment is formed with a first heat dissipating channel 7 a. An end of the first heat dissipating channel is formed with a first air inlet 2201. An opposite end of the lamp shell 2 is formed with a venting hole 222 (at an upper portion of the lamp neck 22). Air flows into the first heat dissipating channel 2201 and flows out from the venting hole 222 for bringing out heat in the first heat dissipating channel 7 a (primarily, heat of the working power source 5). As for the path of heat dissipation, heat generated from the heat-generating components of the working power source 5 is transferred to air (around the heat-generating components) in the first heat dissipating channel 7 a by thermal radiation first, and then external air enters the first heat dissipating channel 7 a by convection to bring out internal air to make heat dissipation. In this embodiment, the venting hole 222 at the lamp neck 22 can also make direct heat dissipation.

As shown in FIGS. 1, 2 and 4, a second heat dissipating channel 7 b is formed in the fins and the base 13 of the heat sink 1. The second heat dissipating channel 7 b has a second air inlet 1301. In this embodiment, the first air inlet 2201 and the second air inlet 1301 share the same opening formed on the light board 3. This will be described in more detail later. Air flows from outside of the LED lamp into the second air inlet 1301, passes through the second heat dissipating channel 7 b and finally flows out from spaces between the fins 11 so as to bring out heat of the fins 11 to enhance heat dissipation of the fins 11. As for the path of heat dissipation, heat generated from the LED chips is conducted to the heat sink 1, the fins 11 of the heat sink 1 radiate the heat to surrounding air, and convection is performed in the second heat dissipating channel 7 b to bring out heated air in the heat sink 1 to make heat dissipation.

FIG. 5 is a perspective view of the LED lamp of an embodiment, which shows assembling of the heat sink 1 and the lamp cover 4. FIG. 6 is a structural schematic view of FIG. 5 without the light output surface 43. As shown in FIGS. 5 and 6, in this embodiment, the lamp cover 4 includes a light output surface 43 and an end surface 44 with a vent 41. Air flows into both the first heat dissipating channel 7 a and the second heat dissipating channel 7 b through the vent 41. When the LED chips 311 (shown in FIG. 6) are illuminated, the light passes through the light output surface 43 to be projected from the lamp cover 4. In this embodiment, the light output surface 43 may use currently available light-permeable material such as glass, PC, etc. The term “LED chip” mentioned in all embodiments of the invention means all light sources with one or more LEDs (light emitting diodes) as a main part, and includes but is not limited to an LED bead, an LED strip or an LED filament. Thus, the LED chip mentioned herein may be equivalent to an LED bead, an LED strip or an LED filament.

As shown in FIGS. 5 and 6, in this embodiment, an inner reflecting surface 4301 is disposed inside the light output surface 43 of the lamp cover 4. The inner reflecting surface 4301 is disposed in the inner circle of the array of LED chips 311. In an embodiment, an outer reflecting surface 4302 is disposed in the outer circle of the array of LED chips 311. The outer reflecting surface 4302 corresponds to the LED chips 311 on the light board 3. The arrangement of both the inner reflecting surface 4301 and the outer reflecting surface 4302 is used for adjusting a light emitting range of the LED chip set 31 to make the light concentrated and to increase brightness in a local area. For example, under the condition of the same luminous flux, illuminance of the LED lamp can be increased. In one example, all the LED chips 311 in this embodiment are mounted on the bottom side of the light board 3 (in a using status). In this embodiment, the LED lamp of the present embodiment does not emit lateral light from the LED chips 311. When working, the primary light emitting surfaces of the LED chips 311 are completely downward. At least 60% of the light from the LED chips 311 are emitted through the light output surface 43 without reflection. As a result, in comparison with those LED lamps with lateral light (the lateral light is reflected by a cover or a lampshade to be emitted downward, and in theory there must be part of light loss in the process of reflection.) The LED chips 311 in this embodiment possess better light emitting efficiency. In one example, under the condition of the same lumen value (luminous flux), the LED lamp in the present embodiment possesses higher illuminance. And the emitted light can be concentrated to increase illuminance in a local area by the arrangement of both the inner reflecting surface 4301 and the outer reflecting surface 4302, for example, in an area under the LED lamp between 120 degrees and 130 degrees (a light emitting range under the LED lamp between 120 degrees and 130 degrees). When the LED lamp is installed at a relatively high position, in the same angular range of light emitting, the lit area of the LED lamp still satisfies the requirement and illuminance in this area can be higher.

The inner reflecting surface 4301 is used for reflecting part of light emitted from the innermost LED chips 311 of the LED chip set 31. The outer reflecting surface 4302 is used for reflecting part of light emitted from the outermost LED chips of the LED chipset 31. The outermost LED chips 311 are greater than the innermost LED chips 311 in number. The outer reflecting surface 4302 is greater than the inner reflecting surface 4301 in area. Because the outermost portion of the LED chip set 31 includes more LED chips than the innermost portion, larger reflecting area is beneficial to regulate light output.

In this embodiment, the inner reflecting surface 4301 and the outer reflecting surface 4302 have first area A1 and second area A2, respectively. The LED chips 311 in the outermost portion of the LED chip set 31 and in the innermost portion of the LED chip set 31 are N1 and N2 in number, respectively. Their relationship is:

(A1/N1):(A2/N2)=0.4˜1

When the ratio of area of the inner reflecting surface 4301 corresponding to a single LED chip 311 in the innermost portion of the LED chip set 31 to area of the outer reflecting surface 4302 corresponding to a single LED chip 311 in the outermost portion of the LED chip set 31 falls in the above range, both the LED chips 311 in the innermost portion of the LED chip set 31 and the LED chips 311 in the outermost portion of the LED chip set 31 have a better effect of light output.

As show in FIGS. 5 and 6, in this embodiment, in order to prevent dust from covering on the LED chips 311 to reduce light efficiency of the LED chips or affect heat dissipation of the LED chips 311, the LED chips 311 may be received in a sealed room. For example, a sealed chamber 9 is formed between the light output surface 43, the inner reflecting surface 4301, the outer reflecting surface 4302 and the light board 3 (this term “sealed” mentioned here may mean “without obvious pores”, not including unavoidable gaps in an assembling process). In some embodiments, when omitting both the inner and outer reflecting surfaces 4301, 4302, the sealed chamber 9 is formed between the light output surface 43 and the light board 3 or between the light output surface 43, the heat sink 1 and the light board 3.

FIG. 7 is a perspective view of another embodiment of the LED lamp of the invention. It differs from the above embodiment by holes formed in the chamber 9. FIG. 8 is a schematic view of FIG. 7 without the light output surface 43. As shown in FIGS. 7 and 8, in some embodiments, a chamber 9 is formed between the light cover 4 and the light board 3. In detail, the chamber 9 is formed between the light output surface 43, the inner reflecting surface 4301, the outer reflecting surface 4302 and the light board 3 and the LED chips of the light board 3 are located in the chamber 9. The chamber 9 has first apertures 91 and second apertures 92. The first apertures 91 are configured to communicate with the outside, and the second apertures 92 are configured to communicate simultaneously with both the first heat dissipating channel 7 a and the second heat dissipating channel 7 b. In an aspect of heat dissipation, air convection is formed in the chamber 9 to bring out part of heat generated from the LED chips 311, and outside air flows into the LED lamp through the chamber 9 so as to enhance convection in both the first heat dissipating channel 7 a and the second heat dissipating channel 7 b. In some embodiments, both the inner and outer reflecting surfaces 4301, 4302 may be omitted. In one example, a chamber 9 is formed between the light output surface 43 and the light board 3.

As shown in FIG. 7, in some embodiments, the light output surface 43 is provided with a hole to form the first apertures 91. Preferably, the first apertures 91 are annularly located at a circumferential portion of the light output surface 43 to make it not affect the effect of light penetration of the light output surface 43. In an aspect of structure, the light output surface 43 may be thermally deformed while the LED lamp is working. The first apertures 91 makes the light output surface 43 have a deformable space to prevent the light output surface 43 from being deformed to press the heat sink and cause damage of the light output surface 43. In this embodiment, the first apertures 91 are annularly located at a circumferential portion of the light output surface 43. As a result, air convection can be enhanced and structural strength of the light output surface 43 heated can also be reinforced.

As shown in FIG. 8, in some embodiments, the inner reflecting surface 4301 is provided with notches to form the second apertures 92. In this embodiment, the second apertures 92 are annularly located at a circumferential portion of the inner reflecting surface 4301. The ratio of the number of the second apertures 92 to that of the first apertures 91 is about 1:1˜2, preferably, 1:1.5. Thus, air intake and outtake can be balanced. In other embodiments, both the first apertures 91 and the second apertures 92 may also be formed at other portions of the lamp cover 4 such as the light board 3 or the base 13 of the heat sink 1.

As shown in FIGS. 7 and 8, in some embodiments, a chamber 9 is formed between the light cover 4 and the light board 3. In detail, the chamber 9 is formed between the light output surface 43, the inner reflecting surface 4301, the outer reflecting surface 4302 and the light board 3 and the LED chips 311 of the light board 3 are located in the chamber 9. The chamber 9 has pressure release apertures to prevent temperature and pressure in the chamber from being raised by the working LED chips 311. The pressure release aperture may be the first apertures 91 of the light output surface 43, the second apertures 92 of the inner reflecting surface 4301, or holes at the heat sink 1 or the light board 3, which communicate with the chamber 9.

FIG. 9 is a schematic view of an end surface 44 of the lamp cover 4 of an embodiment. As shown, the ratio of a total of cross-sectional area of the vent 41 to overall area of the end surface 44 (area of a single side of the end surface 44, such as the side away from the LED chips 311) is 0.01˜0.7. Preferably, the ratio of a total of cross-sectional area of the vent 41 to overall area of the end surface 44 is 0.3˜0.6. More preferably, the ratio of a total of cross-sectional area of the vent 41 to overall area of the end surface 44 is 0.4˜0.55. By limiting the ratio of a total of cross-sectional of the vent 41 to overall area of the end surface 44 to the above ranges, not only can air intake of the vent 41 be guaranteed, but also adjustment of area of the vent 41 is implemented under ensuring structural strength of the end surface 44. When the ratio of area of the vent 41 to area of the end surface 44 is 0.4˜0.55, not only can air intake of the vent 41 be guaranteed to satisfy requirements of heat dissipation of the LED lamp, but also the vent 41 does not affect structural strength of the end surface 44 to prevent the end surface 44 with the vent 41 from being fragile due to collision or pressure.

FIG. 10 is a schematic view of an end surface 44 of the lamp cover 4 of another embodiment. As shown in FIGS. 10 and 11, a periphery of the vent 41 has an enlarged thickness to form rib portions 411. An air guide opening 412 in a direction of air intake of the vent 41 is formed between adjacent two of the rib portions 411. A periphery of the vent 41 with an enlarged thickness can enhance structural strength of the end surface 44 to avoid reduction of overall structural strength due to the vent 41. On the other hand, the air guide opening 412 has an effect of air guiding to make air flowing into the air guide opening 412 have a specific direction. In addition, when the end surface 44 is being formed, the rib portion 411 avoid reduction of overall structural strength of the end surface 44. Thus, the end surface 44 is hard to be deformed because of the vent 41 to increase the yield rate of manufacture. In this embodiment, the rib portions 411 are formed on the side of the end surface 44, which is adjacent to the light board.

As shown in FIG. 11, the thickness of periphery of the vent 41 is greater than that of other portions of the end surface 44 so as to improve strength of the parts around the vent 41 and the effect of air guiding.

As shown in FIG. 9, a diameter of a maximum inscribed circle of the vent 41 is less than 2 mm, preferably, 1.0˜1.9 .mm. As a result, both bugs and most dust can be resisted, and venting efficiency of the vent 41 can be kept great enough. In one example, alternatively, the vent 41 defines both a length direction and a width direction, i.e. the vent has a length and a width, and the length is greater than the width. The largest width of inscribed circle of the vent 41 may be less than 2 mm. In an embodiment, the largest width is from 1 mm to 1.9 mm. In addition, the largest width of the vent 41 may be greater than 1 mm. If the width of the vent 41 is less than 1 mm, then more pressure is required to push air to enter the vent 41, which is advanced for venting.

FIGS. 12A˜12G show shapes of some embodiments of the vent 41. As shown in FIGS. 12A-12G, the vent 41 may be circular, strip-shaped, arced, trapezoidal, diamond or their combination. As shown in FIG. 12A, when the vent 41 is configured to be circular, its diameter should be less than 2 mm to resist bugs and most dust and venting efficiency of the vent 41 can be kept great enough. As shown in FIGS. 12B and 12C, when the vent 41 is configured to be strip-shaped or arced, its width should be less than 2 mm to accomplish the above effects. As shown in FIG. 12D, when the vent 41 is configured to be trapezoidal, its lower base should be less than 2 mm to accomplish the above effects. As shown in FIG. 12E, when the vent 41 is configured to be round-cornered rectangular, its width should be less than 2 mm to accomplish the above effects. As shown in FIGS. 12F and 12G, when the vent 41 is configured to be triangular or drop-shaped, a diameter of its maximum inscribed circle should be less than 2 mm.

In some embodiments, the vent 41 on the end surface 44 is multiple in number. For example, the vents 41 may be annularly arranged on the end surface 44 for even air intake. The vents 41 may also be radially arranged on the end surface 44. The vents 41 may also be irregularly arranged.

In FIG. 12A, there are two broken lines on the end surface 44. The inner broken line represents a position the first air inlet 2201 (as shown in FIG. 2) is projected onto the end surface 44. The region within the inner broken line is defined as a first portion (first opening region 433). The region between the inner circle and the outer circle is defined as a second portion (second opening region 434). In this embodiment, the first air inlet 2201 is projected onto the end surface in an axis of the LED lamp to occupy an area on the end surface 44, it is the first portion (first opening region 433). The other area on the end surface 44 is the second portion (second opening region 434). The vent 41 in the first portion is greater than the vent 41 in the second portion in area. Such an arrangement is advantageous to making most air flow into the first heat dissipating channel 7 a for better effect of heat dissipation to the power source 5 and reduction of rapidly aging of electronic components of the power source 5. These features are also available to the vent 41 in other embodiments.

In other embodiments, the first air inlet 2201 is projected onto the end surface 44 in an axis of the LED lamp to occupy an area on the end surface 44, which may be a first portion (first opening region 433). The other area on the end surface 44 may be a second portion (second opening region 434). The vent 41 in the first portion is greater smaller than the vent 41 in the second portion in area. As a result, heat of the fins 11 can be better dissipated to perform better heat dissipation to the LED chips 311 and prevent a region around the LED chips 311 from forming high temperature. In detail, area of both the first portion and the second portion can be selected according to actual requirements.

In some applications, there may be a limit of overall weight of an LED lamp. For example, when an LED lamp adopts an E39 head, its maximum weight limit is 1.7 Kg. Thus, besides the fundamental elements such as a power source, a lamp cover and a lamp shell, in some embodiments, weight of a heat sink is limited within 1.2 Kg. For some high-power LED lamps, the power is about 150 W˜300 W, and their luminous flux can reach 20000 lumens to 45000 lumens. Under a limit of weight, a heat sink should dissipate heat from an LED lamp with 20000˜45000 lumens. Under a condition of heat dissipation of natural convection, usually power of 1 W needs area of heat dissipation of at least 35 square cm. The following embodiments intend to reduce area of heat dissipation for power of 1 W under guarantee of a receiving space of the power source 5 and effect of heat dissipation. Under a precondition of weight limit of the heat sink 1 and limit of the power source 5, the best effect of heat dissipation can be accomplished.

As shown in FIGS. 1 and 2, in this embodiment, the LED lamp includes passive heat dissipating elements which adopt natural convection and radiation as a heat dissipating manner without any active heat dissipating elements such as a fan. The passive heat dissipating element in this embodiment includes a heat sink 1 composed of fins 11 and a base 13. The fins 11 radially extend from and connect to the base 13. When using the LED lamp, at least part of heat from the LED chips 311 is conducted to the heat sink 1 by thermal conduction. At least part of heat occurring from the heat sink 1 is transferred to external air by thermal convection and radiation.

A diameter of a radial outline of the heat sink 1, in a hanging status as shown in the figures, tapers off upward or is substantially in a taper shape for a better match with a lampshade. When the heat sink 1 in this embodiment is dissipating heat, at least part of heat is thermally radiated to air therearound to perform heat dissipation. An important factor of thermal radiation is emissivity. To improve emissivity of the heat sink 1, surfaces of the heat sink in this embodiment are specially treated. For example, surfaces of the heat sink 1 are provided with radiation heat-dissipating paint or electrophoretic coating to increase efficiency of thermal radiation and to rapidly dissipate heat of the heat sink 1. Another solution is forming a nanostructured porous alumina layer on the surfaces of the fins 11 by anodization in an electrolyte to form a layer of nanostructured porous alumina. As a result, ability of heat dissipation of the fins 11 can be enhanced without adding the number of the fins 11. Alternatively, the surfaces of the fins 11 may be coated with an anti-thermal-radiation layer to reduce thermal radiation between the fins 11. This can make more heat radiate to air. The anti-thermal-radiation layer may adopt paint or oxide coating, in which the paint may be normal paint or radiation heat dissipation paint. To further enhance heat dissipating effect of the heat sink 1. As shown in FIGS. 2, 4 and 5, the base 13 of the heat sink 1 has a lower end 133 located under the base 13, i.e. both the lower end 133 and the light board 3 are located on the same side. In this embodiment, the lower end 133 protrudes from the light board 3 in an axis of the LED lamp. In a using (hanging) status of the light board 3 being downward, the lower end 133 is lower than the light board 3 in position. As a result, the position of the lower end 133 can protect the LED board 3. When collision occurs, the lower end 133 will collide first to prevent the light board 3 from colliding. As shown in FIGS. 2 and 4, in another aspect, the base 13 has a recess 132 in which the light board 3 is placed. The recess 132 is of a cylindrical shape or a substantially cylindrical shape, or a cylindrical platform structure. When the recess 132 is of a cylindrical shape, a diameter of the cylinder is less than that of the base 13. The recess 132 in the base 13 is advantageous to reducing a glare effect of the LED lamp and improve direct vision and comfort of users (inner walls of the recess 132 screen at least part of lateral light from the LED chips 311 to decrease glare). In some embodiments, the base 13 may have no recess. In some embodiments, to make both the light board 3 and the heat sink 1 have maximum contact area to guarantee a heat dissipation effect, a surface of the base 13 is a flat plane.

FIG. 13 is a perspective view of an LED lamp of an embodiment of the present invention. As shown in FIGS. 2 and 13, another side of the base 13 of the heat sink 1, which is opposite to the lower end 133, has a back side 134. An end of each fin 11 extends to connect with the back side 134. Thus, At least part of each fin 11 projects from the LED light board 3 in an axis. In one example, in an axial direction of the LED lamp, each of the fins 11 is formed with an extension portion 1101 between the back side 134 of the base 13 and the light board 3. The extension portions 1101 can increase area of heat dissipation of the fins 11 and improve an effect of heat dissipation. In addition, the extension portion 1101 does not increase overall height of the LED lamp so as to be advantageous to controlling overall height of the LED lamp.

FIG. 14 is a cross-sectional view of the LED lamp of this embodiment. As shown, in this embodiment, the back side 134 of the base 13 is slanted. For example, when the LED lamp is being hung, in an inward radial direction, the back side 134 is upwardly slanted. In another aspect, in a radial direction of the LED lamp toward an axis of the LED lamp, an axial distance from the back side 134 to the light board 3 is progressively increased. Such an arrangement is advantageous to convection air is introduced along the back side 134 to bring out heat of the back side 134 and prevents the back side 134 from obstructing air flowing into.

As shown in FIGS. 2 and 5, in a using status, the light board 3 is downwardly arranged, a position of the lower end 133 is lower than an end side 44 of the lamp cover 4 and the light output surface 43. As a result, when packing, transporting or using the LED lamp, if collision occurs, then the lower end 133 will collide to prevent the lamp cover from colliding to damage the end side 44 or the light output surface 43.

As shown in FIGS. 2 and 5, a receiving space (indent 132) is encompassed by the lower ends 133 for receiving the lamp cover 4. Height of the lamp cover 4 received in the receiving space does not project from the lower end 133. Height of the LED lamp mainly includes height of the lamp shell 2, height of the heat sink 1 and height of the lamp cover 4. In this embodiment, the lamp cover 4 does not project from the lower end 133, this can control overall height of the lamp and the lamp cover 4 does not increase overall height of the lamp. In another aspect, the heat sink 1 additionally increases heat dissipating portion (downward protruding part of the light board 3 corresponding to the lower end 133). In other embodiments, a part of the lamp cover 4 may project from the lower end 133.

As shown in FIGS. 2, 4 and 5, a gap is kept between the end side 44 and the light board 3 to form a room 8. The room 8 communicates with both the first air inlet 2201 of the first heat dissipating channel 7 a and the second air inlet 1301 of the second heat dissipating channel 7 b. Air flows into the room 8 through the vent 41 of the end side 44 and then flows into both the first heat dissipating channel 7 a and the second heat dissipating channel 7 b. The room 8 allows air therein to mix and the mixed air is distributed according to negative pressure (resulting from temperature difference) of both the first and second heat dissipating channels 7 a, 7 b so as to make distribution of air more reasonable.

In this embodiment, when a passive heat dissipation manner (fanless) is adopted, the ratio of power (W) of the LED lamp to heat dissipating surface area (square cm) of the heat sink 1 is 1:20˜30. That is, each watt needs heat dissipating surface area of 20˜30 square cm for heat dissipation. Preferably, the ratio of power of the LED lamp to heat dissipating surface area of the heat sink 1 is 1:22˜26. More preferably, the ratio of power of the LED lamp to heat dissipating surface area of the heat sink 1 is 1:25. The first heat dissipating channel 7 a is formed in the lamp shell 2, the first heat dissipating channel 7 a has the first air inlet 2201 at an end of the lamp shell 2, and another end of the lamp shell 2 has the venting hole 222. Air flows into the first air inlet 2201 and flows out from the venting hole 222 to bring out heat in the first heat dissipating channel 7 a. The second heat dissipating channel 7 b is formed in the fins 11 and the base 13 and the second heat dissipating channel 7 b has the second air inlet 1301. Air flows into the second air inlet 1301, passes the second heat dissipating channel 7 b, and finally flows out from the spaces between the fins 11 to bring out heat radiated from the fins 11 to air therearound and enhance heat dissipation of the fins 11. By both the first and second heat dissipating channels 7 a, 7 b, efficiency of natural convection can be increased. This reduces required area of heat dissipation of the heat sink 1 so as to make the ratio of power of the LED lamp to heat dissipating area of the heat sink 1 be between 20 and 30. In this embodiment, overall weight of the LED lamp is less than 1.7 Kg. When the LED lamp is provided with power of about 200 W (below 300 W, preferably, below 250 W), the LED chips 311 are lit up and emit luminous flux of at least 25000 lumens.

As shown in FIG. 1, weight of the heat sink 1 in this embodiment accounts for above 50% of weight of the LED lamp. In some embodiments, weight of the heat sink 1 accounts for 55˜65% of weight of the LED lamp. Under this condition, volume of the heat sink 1 accounts for above 20% of volume of the overall LED lamp. Under a condition of the same thermal conductivity of the heat sink 1 (i.e. overall heat sink 1 uses a single material or two different materials with almost identical thermal conductivity), the larger the volume occupied by the heat sink 1 is, the larger the heat dissipating area which can be provided by the heat sink 1 is. As a result, when volume of the heat sink 1 accounts for above 20% of volume of the overall LED lamp, the heat sink 1 may have more usable space to increase its heat dissipating area. Considering the arrangement space of the power source 5, the lamp cover 4 and the lamp shell 2, preferably, volume of the heat sink 1 accounts for 20%˜60% of volume of the overall LED lamp. More preferably, volume of the heat sink 1 accounts for above 25˜50% of volume of the overall LED lamp. Accordingly, although the overall size of the LED lamp is limited and the space for receiving the power source 5, the lamp cover 4 and the lamp shell 2 must be kept, volume of the heat sink 1 can still be maximized. This is advantageous to design of overall heat dissipation of the LED lamp.

FIG. 15 is top view of the heat sink 1 of the LED lamp of an embodiment. As shown, the heat sink 1 suffers the above volume limit, so at least part of the fins 11 are extended outward in a radial direction of the LED lamp with at least two sheets at an interval. By such an arrangement, the fins 11 in a fixed space can have larger area of heat dissipation. In addition, the extended sheets form support to the fins 11 to make the fins firmly supported on the base 13 to prevent the fins 11 from deflecting.

In detail, as shown in FIG. 15, the fins include first fins 111 and second fins 112. The bottoms of both the first fins 111 and the second fins 112 in an axis of the LED lamp connect to the base 13. The first fins 111 interlace with the second fins 112 at regular intervals. Being projected from the axial direction of the LED lamp, each of the second fins 112 is to be seen as a Y-shape. Such Y-shaped second fins 112 can have more heat dissipating area under a condition of the heat sink 1 occupying the same volume. In this embodiment, both the first fins 111 and the second fins are evenly distributed on a circumference, respectively. Every adjacent two of the second fins 112 are symmetrical about one of the first fins 111. In this embodiment, an interval between one of the first fins 111 and adjacent one of the second fins 112 is 8˜12 mm. In general, to make air flow in the heat sink 1 smooth and to make the heat sink perform a maximum effect of heat dissipation, intervals between the fins 11 should be as uniform as possible.

As shown in FIGS. 8 and 15, at least one of the fins 11 is divided into two portions in a radial direction of the LED lamp. Thus, a gap between the two portions forms a passage to allow air to pass. In addition, the projecting area of the gap directly exactly corresponds to an area that the LED chips 311 are positioned on the LED board 3 to enhance convection and improve an effect of heat dissipation to the LED chips 311. In an aspect of limited overall weight of the LED lamp, part of the fins 11 divided with a gap reduces the amount of the fins 11, decreases overall weight of the heat sink 1, and provides a surplus space to accommodate other elements.

FIG. 16 is an enlarged view of portion E in FIG. 15. As shown in FIGS. 15 and 16, the fins 11 includes first fins 111 and second fins 112. Each of the first fins 11 is divided into two portions in a radial direction of the LED lamp, i.e. a first portion 111 a and a second portion 111 b. The two portions are divided with a gap portion 111 c. The first portion 111 a is located inside the second portion 111 b in a radial direction. Each of the second fins 112 has a third portion 112 a and a fourth portion 112 b extending therefrom. The fourth portions 112 b are located radially outside the third portions 112 a to increase space utilization and make the fins have more heat dissipating are for heat dissipation. As shown in FIG. 16, the third portion 112 a is connected to the fourth portion 112 b through a transition portion 113. The transition portion 113 has a buffer section 113 a and a guide section 113 b. At least one or both of the buffer section 113 a and the guide section 113 b are arced in shape. In other embodiment, both the buffer section 113 a and the guide section 113 b are formed into an S-shape or an inverted S-shape. The buffer section 113 a is configured to prevent air radially outward flowing along the second fins 112 from being obstructed to cause vortexes. Instead, the guide section 113 b is configured to be able to guide convection air to radially outward flow along the second fins 112 without interference (as shown id FIG. 17).

As shown in FIG. 16, one of the second fins 112 includes a third portion 112 a and two fourth portions 112 b. The two fourth portions 112 b are symmetrical about the third portion 112 a. In other embodiments, one of the second fins 112 may include a third portion 112 a and multiple fourth portions 112 b such as three or four fourth portions 112 b (not shown). The multiple fourth portions 112 b of the second fin 112 are located between two first fins 111.

As shown in FIG. 16, a direction of any tangent of the guide section 113 b is separate from the gap portion 111 c to prevent convection air from flowing into the gap portion 111 c through the guide portion 113 b, such that the poor efficiency of heat dissipation caused by longer convection paths is able to be avoid as well. Preferably, a direction of any tangent of the guide section 113 b is located radially outside the gap portion 111 c. In other embodiments, a direction of any tangent of the guide section 113 b is located radially inside the gap portion 111 c.

As shown in FIG. 13, at least partially of fin 11 has a protrusion 1102 projecting from a surface of the fin 11. The protrusions 1102 extend along an axis of the LED lamp and are in contact with the base 13. A surface of the protrusion 1102 may selectively adopt a cylindrical shape or a regular or an irregular polygonal cylinder. The protrusions 1102 increase surface area of the fins 11 to enhance efficiency of heat dissipation. In addition, the protrusions 1102 also form a support effect to the fins 11 to prevent the fins 11 from being inflected in manufacture. In some embodiments, a single fin 11 is divided into two portions in a radial direction of the LED lamp. Each portion is provided with at least one protrusion 1102 to support the two portions. In this embodiment, the protrusion 1102 is located at an end portion of each fin 11 in a radial direction of the LED lamp, for example, at end portions of the first portions 111 a, 111 b (the ends near the gap portion 111 c).

In some embodiments, when each fin 11 is a single piece without the gap portion, the protrusion 1102 may also be disposed on a surface of each fin 11 (not shown) to increase surface area of heat dissipation of the fins 11 and have a support effect to the fins 11 to prevent the fins 11 from being inflected in manufacture.

FIG. 18 is a bottom view of the LED lamp of FIG. 1 without the lamp cover 4. FIG. 19 is an enlarged view of portion A in FIG. 18. As shown in FIGS. 18 and 19, the heat sink 1 is disposed outwardly of the sleeve 21, and the power source 5 is disposed in the inner space of the sleeve 21. A distance is kept between distal ends of the fins 11 and the sleeve 21. Accordingly, the sleeve 21 which has been heated to be thermally expanded will not be pressed by the fins 11 to be damaged. Also, heat from the fins 11 will not be directly conducted to the sleeve 21 to adversely affect electronic components of the power source 5 in the sleeve 21. Finally, air existing in the distance between the fins 11 and the sleeve 21 of the lamp shell 2 (as shown in FIG. 3) possesses an effect of thermal isolation so as to further prevent heat of the heat sink 1 from affecting the power source 5 in the sleeve 21. In other embodiments, to make the fins 11 have radial support to the sleeve 21, distal ends of the fins 11 may be in contact with an outer surface of the sleeve 21 and another part of the fins 11 are not in contact with the sleeve 21. Such a design may be applied in the LED lamp shown in FIG. 18. As shown in FIG. 18, the light board 3 includes a third aperture 32 for exposing both the first air inlet 2201 of the first heat dissipating channel 7 a and the second air inlet 1301 of the second heat dissipating channel 7 b. In some embodiments, to rapidly dissipate heat from the power source 5, the ratio of cross-sectional area of the first air inlet 2201 to cross-sectional area of the second air inlet 1301 is greater than 1 but less than or equal to 2. In some embodiments, to rapidly dissipate heat from the power source 5, the ratio of cross-sectional area of the second air inlet 1301 to cross-sectional area of the first air inlet 2201 is greater than 1 but less than or equal to 1.5.

As shown in FIGS. 13 and 14, the innermost of the fins 11 in a radial direction of the LED lamp is located outside the venting hole 222 in a radial direction of the LED lamp. In one example, an interval is kept between the innermost of the fins 11 in a radial direction of the LED lamp and the venting hole 222 in a radial direction of the LED lamp. As a result, heat from the fins 11 flowing upward will not gather to the venting hole 222 to keep an interval with the venting hole 222. This avoids heat making air around the venting hole 222 heat up to affect convection temperature speed of the first heat dissipating channel 7 a (the convection speed depends upon a temperature difference between two sides of the first heat dissipating channel 7 a, when air temperature near the venting hole 222 rises, the convection speed will correspondingly slowdown.).

LEDs generates heat while they are emitting. A key parameter in considering of thermal conduction of LEDs is thermal resistance. The smaller the thermal resistance is, the better the thermal conduction is. Primarily, factors of thermal resistance include length of conduction path, conduction area and thermal conductivity of a thermo-conductive material. It can be expressed by the following formula:

Thermal resistance=length of conduction path L/(conduction area S*thermal conductivity)

That is to say, the shorter the conduction path is and the larger the conduction area is, the lower the thermal conductivity is.

As shown in FIG. 18, in this embodiment, the light board 3 includes at least one LED chip set 31 having LED chips 311.

As shown in FIG. 18, in this embodiment, the light board 3 is divided into three areas comprising an inner ring, a middle ring and an outer ring. All the LED chip sets 31 are located in the three areas. In one example, the inner ring, the middle ring and the outer ring are separately mounted by different amount of LED chip sets 31. In another aspect, the light board 3 includes three LED chip sets 31. The three LED chip sets 31 are respectively located in the inner ring, the middle ring and the outer ring. Each of the LED chip sets 31 separately in the inner ring, the middle ring and the outer ring has at least one LED chip 311.

Four hypothetical circle lines are defined on the light board 3 as shown in FIG. 18. The outer ring is defined by the area between the outermost two circle lines of the four, the inner ring is defined by the area between the innermost two circle lines of the four, and the middle ring is located between the two areas mentioned above. In another embodiment, the light board 3 is separated into two rings (areas), and the chip sets 31 are divided to be mounted on the two rings.

FIG. 20 is a schematic view of the combination of the fins 11 and the LED chips 311 of one embodiment. As shown in FIGS. 18 and 20, in this embodiment, when at least one fin 11 is projected onto the plane on which the LED chip sets 31 are located along the axial direction of the LED lamp, a projection of the fin 11 at least touches at least one LED chip 311 of the LED chip set 31. In detail, when at least one fin 11 is projected onto a plane on which the LED chip set 31 is located along the axial direction of the LED lamp, a projection of the fin 11 at least touches at least one LED chip 311 of the LED chip set 31 in the inner ring, the middle ring or the outer ring. As shown in FIG. 20, the projection of the fin 11 touches an LED chip 311. As indicated by the arrow in the figure, it is a heat dissipating path of the LED chip 311 and the fin 11. As shown in FIG. 21, the projection of the fin 41 does not touch the LED chip 311 in the figure. As indicated by the arrow in the figure, it is a heat dissipating path of the LED chip 311 and the fin 11. It can be seen that the heat dissipating path of the latter is longer than the former's. As a result, by means of a projection of a fin at least touching at least one LED chip 311 of the LED chip set 31 in the inner ring, the middle ring or the outer ring, a heat dissipating path of the LED chip 311 can be shortened. This can reduce thermal resistance to be advantageous to thermal conduction. Preferably, a fin 11 is projected onto a plane on which the LED chip set 31 is located along the axial direction of the LED lamp, a projection of any fin 11 (the first fin 111 or the second fin 112) at least touches at least one LED chip 311 of the LED chip set 31.

In this embodiment, the LED chip sets 31 in outer rings corresponding to the fins 11 are greater than the LED chip sets 31 in inner rings in number. Here the term “corresponding to” means projection relationship in the axial direction of the LED lamp, for example, when the LED chip sets 31 in outer rings are projected onto the fins 11 in the axial direction of the LED lamp, the fins 11 to which the LED chips 31 in outer rings correspond are located on a relatively outer portion of the heat sink 1. Here the LED chip sets 31 in outer rings have more LED chips 311 in number, so they need more fins 11 (area) to implement heat dissipation.

As shown in FIGS. 1 and 18, the light board 3 has an inner border 3002 and an outer border 3003. Both the inner border 3002 and the outer border 3003 separately upward extend along the axial direction of the LED lamp to form a region. An area of part of the fins 11 inside the region is greater than an area of part of the fins 11 outside the region. As a result, the most of the fins 11 can correspond to the light board 3 (a shorter heat dissipating path) to enhance heat dissipating efficiency of the fins 11 and increase effective area of heat conduction of the fins 11 to the LED chips 311.

As shown in FIGS. 3, 5 and 18, a reflecting region 3001 is disposed in a region between the inner ring and an outer edge of the light board 3 to reflect the upward light to the light output surface 43. This can reduce loss of light in an opposite direction of light output in the axial direction of the LED lamp to increase overall intensity of light output.

As shown in FIGS. 4 and 29, the light board 3 is formed with a third aperture 32 separately communicating with the first heat dissipating channel 7 a and the second heat dissipating channel 7 b. For example, the third aperture 32 communicates with spaces between the fins 11 and the chamber of the lamp shell 2 to form air convection paths between the spaces between the fins 11 and between the chamber of the lamp shell 2 and the outside of the Led lamp. The third aperture 32 is located inside the inner ring of the LED lamp. Thus, it would not occupy the space of the reflecting region 3001 to affect reflective efficiency. In detail, the third aperture 32 is located at a central region of the light board 3 and both the first air inlet 2201 and the second air inlet 1301 make air intake through the same aperture (the third aperture 32). In one example, after convection air passes through the third aperture 32, and then enters the first air inlet 2201 and the second air inlet 1301. The third aperture 32 is located at a central region of the light board 3, so both the first air inlet 2201 and the second air inlet 1301 can commonly use the same air intake. Thus, this can prevent occupying an excessive region of the light board 3 and prevent the usable regional area of the light board 3 for disposing the LED chips 311 from decreasing due to multiple air intakes. On the other hand, the sleeve 21 corresponds to the third aperture 32, so convection air may have an effect of thermal isolation to prevent temperatures inside and outside the sleeve 21 from mutually affecting each other when air enters. In other embodiments, if both the first air inlet 2201 and the second air inlet 1301 are located at different positions, then the third aperture 32 may be multiple in number to correspond to both the first air inlet 2201 and the second air inlet 1301. In detail, as shown in FIG. 22, the third aperture 32 may be located at a middle portion or outer portion or between the LED chips 311 to correspond to both the first air inlet 2201 and the second air inlet 1301 stopped

FIG. 23 is a schematic view of the light board 3 in this embodiment. As shown in FIG. 23, in this embodiment, the LED chip sets 31 are at least two in number. The at least two LED chip sets 31 are annularly arranged on the light board 3 in order. Each LED chip set 31 includes at least one LED chip 311. Each LED chip 311 of one of the LED chip sets 31 on the light board 3 is radially interlacedly arranged with any one LED chip 311 of adjacent one of the LED chip sets 31 on the light board 3. That is, the LED chips 311 of different LED chip sets 31 are located in different directions in a radial direction of the LED lamp. In one example, if any line starting with the axis of the LED lamp and extending toward a radial direction of the LED lamp cuts two or more of the LED chips 311, then it will cut different positions of these two or more LED chips 311 and will not cut the same positions of these two or more LED chips 311. As a result, if there is convection on the light board 3 and air radially flows on the light board 3, the contact between air and the LED chips 311 will be more sufficient and a better effect of heat dissipation will be obtained because of the airflow paths. In addition, in the aspect of lighting effect, such distribution of the LED chips 311 is more advantageous to uniformity of light output.

FIGS. 24A˜24C are perspective views of the power source 5 of one embodiment at different viewpoints. FIG. 24D is a main view of the power source 5 of one embodiment. The power source 5 is electrically connected to the LED chips 311 to power the LED chips 311. As shown in FIGS. 24A˜24C, the power source 5 includes a power board 51 and a plurality of electronic components mounted thereon.

As shown in FIGS. 1, 2, 3 and 4, the lamp shell 2 includes the lamp head 23, the lamp neck 22 and the sleeve 21. The lamp head 23 connects to the lamp neck 22 which connects to the sleeve 21. The sleeve 21 is located in the heat sink 1 (in the axial direction of the LED lamp, all or most of the sleeve 21, for example, at least 80% of height of the sleeve 21, does not exceed the heat sink 1). The lamp neck 22 projects from the heat sink 1. Both the sleeve 21 and the lamp neck 22 can provide sufficient space to receive the power source 5 and perform heat dissipation, especially for the power source 5 of a high power LED lamp (in comparison with a low power LED lamp, a power source of a high power LED lamp has more complicated composition and larger size). The power source 5 is received in both the lamp neck 22 and lamp head 23. Total height of the lamp neck 22 and the lamp head 23 is greater than height of the heat sink 1 so as to provide more space for receiving the power source 5. The heat sink 1 is separate from both the lamp neck 22 and the lamp head 23 (not overlap in the axial direction, the sleeve 21 is received in the heat sink 1). Thus, the power source 5 in both the lamp neck 22 and the lamp head 23 is affected by the heat sink 1 slightly (heat of the heat sink 1 would not be conducted to the lamp neck 22 and the lamp head 23 along a radial direction). In addition, the configuration of height of the lamp neck 22 is advantageous to the chimney effect of the first heat dissipating channel 7 a to guarantee convection efficiency of the first heat dissipating channel 7 a. In other embodiments, height of the lamp neck 22 is at least 80% of height of the heat sink 1 to accomplish the above function. The sleeve 21 is made of a thermoisolated material to prevent mutual influence of heat from the fins and the power source.

As shown in FIG. 2, the second air inlet 1301 is located in a lower portion of the heat sink 1 and radially corresponds to an inner side or the inside of the heat sink 1, i.e. the second air inlet 1301 radially corresponds to the inner side or the inside of the fins 11. The inner side or the inside of the fins 11 corresponds to an outer wall (a radially inner side of the fins 11, which nears or abuts against the sleeve 21) of the sleeve 21 of the lamp shell 2. Thus, after convection air flows into the second air inlet 1301, it flows upward along the outer wall of the sleeve 21 to perform convection and radially dissipates heat in the inner side or the inside of the fins 11 and the outer wall of the sleeve 21 to implement an effect of thermal isolation. That is, this can prevent heat of the heat sink 1 is conducted from the outer wall of the sleeve 21 to the inside of the sleeve 21 not to affect the power source 5. From the above, the second heat dissipating channel 7 b can not only enhance heat dissipation of the fins 11, but also implement an effect of thermal isolation. Make a positional comparison between the second air inlet 1301 and the LED chips 311, the second air inlet 1301 is located radially inside all of the LED chips 311.

FIG. 25 is a cross-sectional view of the LED lamp of another embodiment. FIG. 26 is a schematic view of arrangement of the convection channels in the LED lamp. As shown in FIGS. 25 and 26, in some embodiments, a fundamental structure of the LED lamp is identical to the LED lamp shown in FIG. 1. In some embodiments, the sleeve 21 has an upper portion and a lower portion. The upper portion is connected to the lower portion through an air guiding surface 216. A diameter of cross-section of the air guiding surface 216 downward tapers off along the axis of the LED lamp (along the convection direction of the first heat dissipating channel 7 a). That is, the air guiding surface 216 can guide air in the second heat dissipating channel 7 b toward the radial outside of the heat sink 1 so as to make air be in contact with more area of the fins 11 to bring out more heat of the fins 11. The sleeve 21 includes a first portion and a second portion in the axial direction. The second portion is a part of the sleeve 21 below the air guiding surface 216 (including the air guiding surface 216). The first portion is the other part of the sleeve 21 above the air guiding surface 216 (but not including the air guiding surface 216). Electronic components of the power source 5, which are located in the second portion of the sleeve 21, include heat intolerance elements such as capacitors, especially electrolytic capacitors so as to make the heat intolerance elements work in low temperature environment (near the first air inlet 2201). In other embodiments, high heat-generating elements may be disposed in the second portion of the sleeve 21, such as resistors, inductors and transformers. As for the second heat dissipating channel 7 b, when convection air flows into the second heat dissipating channel 7 b and reaches the lower portion of the sleeve 21, the convection air would lean against the outer wall of the sleeve 21 to rise. This can generate an effect of thermal isolation, i.e. heat of the fins 11 is prevented from being conducted to the inside of the sleeve 21 so that the heat intolerance elements therein would not be affected. When the convection air continues to rise, the convection air will flow outward along radial directions of the fins 11 under the guide of the air guiding surface 216 so as to make the convection air be in contact with more area of the fins 11 to enhance an effect of heat dissipation of the fins 11. In this embodiment, the inner chamber of the sleeve 21 is of a wide-upper-side-and-narrow-lower-side channel structure. This significantly enhances the chimney effect and promotes air flowing in the sleeve 21. In addition, the venting hole 222 can be designed on the lamp neck 22 away from the vent to further improve the chimney effect.

The above depiction has been described with reference to the accompanying drawings, in which exemplary embodiments of the disclosure are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. 

What is claimed is:
 1. An LED (light emitting diode) lamp comprising: a lamp shell including a lamp head, a lamp neck and a sleeve, the lamp head connects to the lamp neck which connects to the sleeve; a passive heat dissipating element having a heat sink connected to the lamp shell, wherein the heat sink comprises fins and a base, the sleeve of the lamp shell is located in the heat sink, the lamp neck projects from the heat sink, height of the lamp neck is at least 80% of height of the heat sink; a power source having a first portion and a second portion, wherein the first portion of the power source is disposed in both the lamp neck and the lamp head of the lamp shell, and the second portion of the power source is disposed in the heat sink of the passive heat dissipating element; a light emitting surface connected to the heat sink of the passive heat dissipating element and comprising LED chips electrically connected to the power source, wherein the light emitting surface and the heat sink are connected to form a heat transferring path from the LED chips to the passive heat dissipating element; a first heat dissipating channel formed in a first chamber of the lamp shell for dissipating heat generated from the power source while the LED lamp is working, and the first chamber is located between bottom of the LED lamp and an upper portion of the lamp neck; a second heat dissipating channel formed in the heat sink and between the fins and the base of the heat sink for dissipating the heat generated from the LED chips and transferred to the heat sink; a lamp cover connected with the heat sink and having a light output surface and an end surface, wherein the end surface is formed with a vent to allow air flowing from outside of the LED lamp into both the first heat dissipating channel and the second heat dissipating channel through the vent; wherein the first heat dissipating channel comprises a first end on the light emitting surface to allow air flowing from outside of the LED lamp into the first chamber, and a second end on the upper portion of the lamp neck of the lamp shell to allow air flowing from inside of the first chamber out to the LED lamp; wherein the second heat dissipating channel comprises a third end on the light emitting surface to allow air flowing from outside of the LED lamp into the second heat dissipating channel, and flowing out from spaces between every adjacent two of the fins; wherein the base of the heat sink has a lower end located under the base, the lower end protrudes from the light emitting surface in an axis of the LED lamp; another side of the base of the heat sink, which is opposite to the lower end, has a back side, an end of each of the fins of the heat sink extends to connect with the back side, when the LED lamp is being hung, in an inward radial direction, the back side is upwardly slanted; wherein the fins of the heat sink include first fins and second fins, each of the first fins is divided into two portions in a radial direction of the LED lamp, the two portions are divided with a gap portion, each of the second fins has a third portion and a fourth portion extending therefrom, the fourth portions are located radially outside the third portions, the third portion is connected to the fourth portion through a transition portion, the transition portion has a buffer section and a guide section, a direction of any tangent of the guide section is separate from the gap portion.
 2. The LED lamp of claim 1, wherein a receiving space is encompassed by the lower ends for receiving the lamp cover, height of the lamp cover received in the receiving space does not project from the lower end.
 3. The LED lamp of claim 2, wherein the light emitting surface includes three LED chip sets, each of the three LED sets has LED chips, the light emitting surface is divided into three areas comprising an inner ring, a middle ring and an outer ring, the three LED chip sets are respectively located in the inner ring, the middle ring and the outer ring, when at least one fin of the heat sink is projected onto a plane on which the LED chip set is located along an axial direction of the LED lamp, a projection of the at least one fin at least touches at least one LED chip of the LED chip set in the inner ring, the middle ring or the outer ring.
 4. The LED lamp of claim 3, wherein any of the fins is projected onto a plane on which the LED chip set is located along the axial direction of the LED lamp, a projection of any of the fins at least touches at least one LED chip of the LED chip set.
 5. The LED lamp of claim 4, wherein the LED chip set in the outer ring corresponding to the fins are greater than the LED chip set in the inner ring in number, the LED chip set in the outer ring has more LED chips than the LED chip set in the inner ring in number.
 6. The LED lamp of claim 5, wherein a third aperture is located in a central region of the light emitting surface, and the third aperture forms an air intake of both the first heat dissipating channel and the second heat dissipating channel.
 7. The LED lamp of claim 6, wherein the light emitting surface has an inner border and an outer border, both the inner border and the outer border separately upward extend along the axial direction of the LED lamp to form a region, an area of part of the fins inside the region is greater than an area of part of the fins outside the region.
 8. The LED lamp of claim 7, wherein the sleeve corresponds to the third aperture.
 9. The LED lamp of claim 8, wherein each LED chip of one of the LED chip sets on the light emitting surface is radially interlacedly arranged with any one LED chip of adjacent one of the LED chip sets on the light emitting surface.
 10. The LED lamp of claim 9, wherein the projecting area of the gap portion directly exactly corresponds to an area that the LED chips are positioned on the light emitting surface.
 11. The LED lamp of claim 10, wherein the first air inlet is projected onto the end surface in an axis of the LED lamp to occupy an area on the end surface, which is defined as a first portion, another area on the end surface is defined as a second portion, and the vent in the first portion is greater than the vent in the second portion in area.
 12. The LED lamp of claim 11, wherein an inner reflecting surface is disposed inside the light output surface of the lamp cover, an outer reflecting surface is disposed in the outer circle of the array of LED chips.
 13. The LED lamp of claim 12, wherein a second chamber is formed between the light output surface, the inner reflecting surface, the outer reflecting surface and the light emitting surface, the LED chips of the light emitting surface are located in the second chamber.
 14. The LED lamp of claim 13, wherein the second chamber has first apertures and second apertures, the first apertures are configured to communicate with the outside, and the second apertures are configured to communicate simultaneously with both the first heat dissipating channel and the second heat dissipating channel.
 15. The LED lamp of claim 14, wherein the light output surface is provided with holes to form the first apertures, the first apertures are annularly located at a circumferential portion of the light output surface.
 16. The LED lamp of claim 15, wherein the inner reflecting surface is provided with notches to form the second apertures, the second apertures are annularly located at a circumferential portion of the inner reflecting surface.
 17. The LED lamp of claim 16, wherein the ratio of the number of the second apertures to that of the first apertures is about 1:1˜2. 